Page being initiated on 22 September 2016

Status: 19 October 2016





Apparently again, our Mammut Saga has still not yet reached its conclusion.


During the course of recent discussions on radar aspects in the Netherlands, between Kees Neisingh and me, the question was razed:- what Mammut antenna system once had been employed in the GAF Mammut bunker in The Hague; also known as Kwartellaan Mammut, as well as 'Moritz Stellung'.


Kees pointed that various sources, among it the German Atlantikwall group, claimed that this bunker had been fit with FuMO 53, as well as a Mammut type F system.

My contradicting opinion, is: that it is known that the Kwartellaan Mammut bunker doesn't fit into any regular GAF bunker design (nomenclature).

Earlier investigation done by Michal Svejgaard and Tim de Mos, came to the conclusion that this bunker type does not reflect German military standards, like consisting of a single room only. As well as lacking anti-gas-provisions and the entire absence of self-protection. Also not possessing an integrated power source (generators), which had been 'sheltered' in a separate bunker construction. 

They therefore concluded that it constituted, most likely, a kind of prototype (Versuchsmuster). It is known that it had been built in 1942, at a time when no regular GAF Mammut systems were in service yet.


Luckily we maintain good contact too Piet Hogendoorn, an active member of the Atlantic Wall group of The Hague. Some time ago he mentioned that it might be possible to visit on occasion the Kwartellaan (Moritz) bunker.


Therefore I suggested to Kees Neisingh, that we should investigate the question our selves!

Finding out - whether my understanding of the state of radar affairs about 1942 is correct.

He agreed enthusiastically to it.


When the time was right we approached the site and entered this unique premise.


My first attention was focussed upon the number of antenna cables provided on either side of the bordering walls.



I was quite relived that we encountered two rows of 12 holes only, reflecting a regular Mammut arrangement (configuration)! An adjacent provision right of it, was entirely free of (drilled) holes

One vertical column for the receiver (most left) and right of it meant for the transmitter signals.



Hence, pointing at the application of a normal GAF Mammut antenna array


However, what we ultimately discovered changed my entire understanding of the regular Mammut F version FuG 203 (FuSE 203?) versus the KM version type FuMO 52.


Let us please go back to what last year had been dealt with:


Early July last year Phil traced in the GB-NA the following document:




Air Scientific Intelligence Technical Translation (to FuG 203)(FuSE 203?)

No. 1

Mammut F

date 13/11/44

Issued by A.D.I. (Science).

By the way, famous R.V. Jones' Office


Within it a controversy was encountered which wasn't in accordance to other sources to our disposal.


Quoting from page 2

        This report is a translation of a German official document captured by Royal Navy at the aircraft reporting station at Trogastel (?)* in Brittany. The equipment used similar radar components to the Freya, but has a large fixed broadside array. The direction of the beam is adjusted by means of an elaborate phaseshifter. Separate arrays and ganged phaseshifters are used for transmission and reception. The range of the station is 300 - 350 kms** on high flying aircraft and the D/F accuracy is of the order of ± ½° over the forward and rearward arcs of sweep of 100°. It is probable that the D/F accuracy would depend on the accuracy of tuning of the transmitter, the permissible tolerance being given as ± 0.1 Mc/s on the normal working frequency of 125 Mc/s.

        The equipment seems to have been developed for the G.A.F. by the German Naval Signals Research Station at Pelzerhaken. It is stated that there are only 15 such equipments,



Accompanied within this interesting document was this sheet:

Der Kompensator FK2


The next quotation was for me rather irritating: Some apparent incorrect details being included in this translated text section.



I at least doubt that its content entirely reflects the real German understanding of the process


But, we also possess a photo of a 'Kompensator' arrangement taken in Denmark 1945, during 'Operation Post Mortem' (end of June - early July 1945).



Do we see a slotted device operating a delay-line coil?

(111 SC 269030 - "US National Archives" courtesy Mike Dean, detail modified by AOB)

Seemingly not!

The second suggestion incorporated within this translation, is about a what they describe being a transformer, which isn't describing what it technically constituted!


And we have brought the real proof!



Marc Simons made a series of Smith Chard plots


It is evident that the tuneable 'stub' which should have been the correct technical description acts as a 'tuneable open-line' device!



Another plot shows a different performance

How was this being commenced?



Stichleitung (stub) tuning being set at number 15

Because the stub was designed as to cope with various line-matching conditions




An X-Ray photo of a genuine Stichleitung device

Please click at this link as to open it in PDF


For detail descriptions covered in our foregoing Mammut Survey contribution (Eine Entdeckungsreise), please consider

Stichleitung Roentgen photo


However, what were the technical implications of the No 1 report translation? 



This provision clearly conflicts to the previously shown 'Kompensator' photo taken in Denmark in 1945.

I therefore rejected this concept, last year.


But, why repeating it then all over again?



On the web, we once came across this photo

Very well matching onto Mike Dean's photo taken during Operation Post Mortem in June/July 1945.


But my system understanding has since recently been shacked by an unexpected discovery.



We are currently looking at the same 'Kompensator' device shown in the foregoing photo

But, where are we actually looking at?

In the beginning I couldn't grasp the implications.



Viewing the 'Kompensator' frame from the rear transmitter side of the 'Kompensator' frame

Is this a fake?


The next discovery is likely pointing more towards a solution.



Doubtless, something essential is lacking, but we may have come a bit closer to the point of understanding what this once was about

Whatever conclusion we finally will draw, one aspect we never should forget: the block on the right-hand side provides a slider contact having on the inner-side a spring-loaded silver conductor acting as an electrical contact.

Such provision needs some mechanical pressure as to assure that energy transfer stays reliably possible.


In the past I have already wondered (considering the Kwartellaan site) that nowhere we can find a trace of the core-conductor essential for coaxial line systems, but a bunch of quite thin quasi winded copper wires (my preliminary guess between 0.2 and 0.3 mm diameter); nor that we have seen traces of broken ceramic rods or other means.


However, somewhere there must exist a connection.


As so often, during the night I waked up and thought it all over again. In a brain wave I remembered the contradiction within the No. 1 report dealing with a delay-line device, discussed previously.


A new (preliminary) hypothesis might have been born.


The succession of the following considerations does not reflect the significance of a finding, but indicates what first popped-up in my mind only.




Viewing a photo of the KM Mammut in Wijk aan Zee



My estimation: twice as broad as the regular KM Mammut array, like the one once mounted on top of the V 143 bunker in Wijk aan Zee.


* Even nowadays, calculating simple antenna systems, the mathematical task being already confronted with equations consisting of n ≥ 500 unknowns; even in our current computer era, is consuming considerable processor time!  Albeit, since decades special antenna design programs are on the market available, like NEC; making calculations much more convenient.  



My basic perception of a type FK1 'Kompensator' device

My further assumption: the inner section in the centre should have differed, for the FK2 type - being fit with a coil like delay-line construction.

However, I doubt that inside the two coaxial tubes left- and right, they once also have implied delay-line-coil-sections.

Because the copper tubes measured briefly outside ca 21 mm (22 mm?). When we assume that the gauge (wall thickness) is ca 1 mm (maybe just a little bit less), only an internal diameter of maximally 19 mm (20 mm?) remaining.

I cannot understand how this could have coped with the contact provision of the 'Stichleitungen' involved. It might have been difficult enough to provide sufficient mechanical stability.

They not only have had to cope with sufficient high-voltage spacing, but with humidity aspects as well.


In both cases the mechanical slot-width being equal

Maybe we should now read instead of 'coaxial antenna connector':- inputs to the left- and right-hand side matching provisions, shown in the forgoing drawing.


To be continued in due course


For those interested to take knowledge of the many foregoing considerations of my rather extensive survey of last year, please activate the next hyperlink

Mammut and Wassermann Technology Survey




On 19 October 2016

Continuing our Survey


Time has been found to proceed with our Kwartellaan Mammut (Moritz) bunker Survey.

My first aim was to continue with Kees Neisingh's measurement notes (in Holland we say: wat in het vat zit verzuurd niet). However, shortly after having put the forgoing part on the web, on 3rd October, we received an e-mail on behalf of Bas de Mos:


Hallo Arthur,

Ik sprak Piet vanmiddag, hij vertelde over jullie bezoek en de update op jouw website over de Mammut, heel interessant om te lezen! Het eerste wat er in me op kwam is dat we wat onderdeeltjes hebben gevonden bij het uitgraven van de 'put' naast de Kompensator (dat sprak tijdens Bunkerdag grappig genoeg bij velen tot de verbeelding in de hoop dat er nog een etage onder zat, maar het blijkt een voorziening te zijn zodat men onder de kabels door kon kruipen). Die onderdeeltjes heb je niet kunnen zien omdat ze op de Badhuisweg liggen maar ik voeg er nu een fototje van bij. Misschien helpt het bij je onderzoek. Schijnbaar heeft het opperhoofd van de Haagse Bunkerploeg helaas ooit al veel koperen onderdelen van de Kompensator gejat en zelfs ingeleverd voor de koperprijs😣 Om verdrietig van te worden, maar des te groter was de vreugde toen we toch nog wat exemplaren vonden.

De generatorbunker ligt er eigenlijk pal naast, één van de radarfunderingen ligt op deze bunker. De ruimte tussen de twee bunkers hebben we vrij nauwkeurig geschat op circa 2 meter door de afstand tussen de ingangen van beide bunkers te meten. Verder heb ik beide bunkers van binnen zo goed mogelijk opgemeten en grotendeels nagetekend. Tussen de bunkers in is het een beetje een raadsel. Ooit was er in de radarbunker een volledige deuropening welke later is dichtgemetseld tot enkel nog een nooduitgang. Dan kwam je dus tussen de twee bunkers in. Mijn eerste theorie was dat het een deur naar buiten was die later niet meer nodig bleek te zijn. Gezien het kleine halletje wat er nog aan lijkt te zitten leek dit me aannemelijk. Later bedachten we dat via de opening misschien de Kompensator naar binnen was gebracht en toen hij stond het dus weer grotendeels dichtgemetseld kon worden. Blijft een beetje een raadsel. Ook een interessant detail is dat er buizen lopen van bunker naar bunker, waarschijnlijk dus doorvoeren voor elektra kabel. Die zie je op de 3D tekening niet doorgetrokken omdat ze bij het tekenen niet op elkaar uit kwamen, in de generatorbunker zitten ze hoog tegen het plafond in de muur en in de radarbunker juist laag. Kan dus zijn dat de ene bunker wat hoger ligt dan de ander o.i.d. Het is wachten op de dag dat de gemeente het uitkijkpunt gaat opknappen, dan kunnen we misschien er achter komen hoe het precies zit tussen de bunkers.

Bas de Mos


He kindly attached a series of photos and drawings, which, for Kees Neisingh and me, were quite exciting. Because we have not (yet) the slightest idea how we should virtually understand the situation we just have discovered ourselves, and the not (yet) visible part forming this strangely constructed, likely experimental, Mammut bunker complex.


First, I doubt how we should proceed explaining - as to how both bunkers once had been designed and were situated (located) to one another.

It is evident, that a dominant radar site necessitates a power section. Consisting, likely, of a mains switching section as well as, in case of power failure, an engine driven generator  which should take over on occasion the mains function on occasion.


After some considerations, I decided to start with this top-view illustration

(Courtesy Bas de Mos)

In my perception, the left-hand bunker could have been designated 'Stromversorgung', the right-hand bunker might have been called 'Funkmess-Bunker- or Raum'.


Because this drawing is most likely to be linked best onto the various photos provided, we should use it first.

One of my considerations, is, as to how can we help you to understand the interactions between the bunker-floor-plan in respect to the various photos provided by Bas de Mos. Maybe debatable, but my choice finally being to modify the foregoing drawing with a range of dedicated pointers.


The various characters will be dealt with hereafter

(Courtesy Bas de Mos, though being, for this purpose, adapted)

If you click on this drawing it can be opened in PDF

The succession of photos and character are purely coincidental. 


Where are we currently looking at first? I designated it 'C'

(Courtesy Bas de Mos)



According my designation named 'a'

(Courtesy Bas de Mos)

I suppose that this might have acted as a base for a transformer or that like.

In the background right we notice, likely, the emergency-exit which leads to the designations 'R'


Designated with the character 'd'

(Courtesy Bas de Mos)

Shown is a ground- or earth-rail.

Down in the rear wall we notice a cable tube, likely leading to the 'radar bunker' on the far right-hand side of the drawing.

When we compare the situation versus the right-hand drawing - we notice that the cables do not straight away lead towards the radar bunker (section). Bas de Mos suggest, that not until The Hague's council will start renovation of the bunker roof, we have no chance finding out how the real situation is constituted.

But we might by then no longer among you!


However, what the function of the two, quite flat, bars fit onto the wall once was I don't know.


Apparently the place where once a (mains) power-switch-board was mounted, likely including fuses. I gave it designation 'e'

(Courtesy Bas de Mos)


Considering the rubber like mountings (anti-vibration) we may regard that a motor-driven--generator was dealt with, which I have designated 'J'; viewed from pointer f

(Courtesy Bas de Mos)

The Germans used in nearly all cases artificial rubber, product-name: Buna; produced in various qualities. Our advantage, German cables and other rubber means are still in useable condition. Which, considering that > 70 years have been passed since - is impossible in case of regular 'natural rubber'.

Reconsidering it, they might have used a single mounting frame (chassis), carrying both an engine as well as a rotary generator (alternator).


Viewing 'J' from a slightly different position

(Courtesy Bas de Mos) 


Standing about arrow position 'b'. In the background we notice a brick-wall designated 'v' closing off, I suppose, the former main entrance (gate)

(Courtesy Bas de Mos) 

On the right-hand side we just notice entering daylight via the gating entrance 'k'.


The quite cramp entrance designated 'k'

(Courtesy Bas de Mos)


Just positioned about pointer 'w'

(Courtesy Bas de Mos)

We have now gone through most of Bas' pictures.


Let us, for practical reason,  reconsider the forgoing drawing again.


However, now focussing at the right-hand radar bunker layout



L ←→ L means the space between the two sockets, call it base-blocks meant for the 'Kompensator' device

'u' constituted the twelve antenna cables on both sides interconnecting the 'Kompensator' device with the huge antenna-array.

When you look carefully, you might notice that there exists a second 'Kompensator' section on the rear side of the 'Kompensator' apparatus.

The one in front was handling the receiver signals, whilst the rear section were managing the transmitter signals.


 In the Wijk aan Zee KM V 143 type bunker it looks similar to the GAF 'Kwartellaan' bunker facility

(Courtesy David and Vincent Kossen)

Viewing at the driving-side of the arrangement: The short shaft-rod once was mechanically interconnected onto the NVK beam-steering provision. (Will be discussed further down)


Without explaining the technology concerned, you might understand wherefore a 'Kompensator' was used for; beam steering

(111 SC 269030 - "US National Archives" courtesy Mike Dean, explaining its principle by AOB)

Please bear in mind, that the huge Mammut antenna arrays were mounted static; as to provide a wider 'search angle' the antenna pattern had to be steered by means of 'phase shifting'. The Germans called this device a 'Kompensator'.


The left-hand 'L' arrow points at this kind of concrete base (mountings)

(Courtesy David and Vincent Kossen)


Let us consider first a wartime drawing showing the principle setup of a GAF Mammut type F station.


A genuine wartime GAF  NVK Mammut type F bunker layout

(NARA, with courtesy of Alain Chazette)

Please be aware that in case of the Kwartellaan radar site, the most left-hand side 'Kompensator' never existed!

One matter should be kept in mind: that the KM Mammut operating room - as well as the GAF Mammut type F operating space did not differ much in size and system layout. Albeit, that the bunker concepts differed entirely.



This photo of a Mammut type F station once had been taken in Denmark during 'Operation Post Mortem', held in June/July 1945

(111 SC 269017 - "US National Archives" courtesy Mike Dean)


The console fit with steering wheel, was, most likely, mounted at the 'M' designated concrete socket base.

It might, however, well have been that practically it didn't looked exactly like this in 1942. But after all what we have discovered so far in this exceptional bunker site, it could have nevertheless, been like this on the other hand. Albeit, the Kwartellaan bunker had been equipped without a rear-watching antenna-array facility!

Simply, because nowhere can be found traces of the additional coaxial cable holes in the according bunker walls. For it a dual set of cables should have been provided, which was clearly not the case. Consisting of sets of 2 x 12 cables on either side of the 'Kompensator'. Additionally should be noticed: - that we cannot find any trace of a second, parallel 'Kompensator' mounting base.


What in my perception is lacking in both bunker sections, are provisions for heating! 


When we get a second chance approaching this bunker site again, we should take extra consideration of remaining signs.


Still stays open to me: the left-hand side bunker rooms designated 'T' and 'S'; I guess, maybe rest rooms for the operators or (partly) storage space?

Where did they had their lavatories?

Another query: where was once their petrol storage? And, how were these two bunkers positioned to one another?

Where do we find the necessary chimney outlets?


Might there once have existed an additional bunker (third) section as well? Albeit, not yet noticed.    


To be continued in due course



By Arthur O. Bauer